Gear-cutting machine



. above-indicated: form having vantageous properties that adapt them for Fall Josnrn (1.0'IBBIEN, or PITTSBURGH, E'ENNSYL'VANIA, AssIcNon, BY

OF ROCHESTER, NEW YORK, A; CORPORATION OF NEW trams, 'IO GLEASON worms,

Yonx.

mnsnn ASSIGN- GEABr-GUTTING MACHINE.

Application filed December 29. 1814.

.To all whom it may concern:

' Be it known-that I, JosErH 0.. OBnmn, a citizen of the United States, and a resident of.Pittsburgh, in the county of Al? legheny and State of Pennsylvania,'have invented a new and useful Im Irovement in Gear-Cutting Machines, of w ich the following isla specification.

My invention relates to toothed gears and to apparatus. for producing them, and it has special reference to gears which are provided with generated teeth that are of nomrectilinear contour, particularly teeth of continuously curved contour across the face of the gear. One object-of my invention isto provide anovel, expeditious and accurateapparatus for generatively forming teeth of the. aboveindicated character upon ear blanks of various kinds,such as whee s, pinions, miters and racks- Another object of my invention is to provide toothed wheels and other gears of the novel and adhigh-speed service and for use in the transmission of heavy loads.

Of the accompanying is an end elevational view, in sectiomof a machine outmy process; Fig. 2 is a front elevational View of themac -'ne illustratedin Fig. 1, with artsbroken'away; Figs. 3, 1, 5 and 6 arediagrammatic plan views showing the cooperative relations between a cutting tool and a gear-blank at four-successive stages of my process, and Figs. 'Tand 8 aredia metral sectional 'viewsshowing a pair of cutting tools adapted for carrying out one modification of my process. 4

. Ordinary strai ht-toothed gears, in which the meshingteetengage each otherialong their full lengths simultaneously, have certain well known disadvantages that render them unsuitable-tor thei transmission of power. at high speedst Among these dis advantages are noisy and destructivejarring, unequal tooth strength at different parts of-the tooth th fact that only one ortwo ofithe teeth. ofeach gear csusbe iii-service at one time These objections are overcomef n the iarnilial. herrin bone s ar ,v b a s ch sea c use? 1 to ma summari y without standing as central drawings, Figure 1 with parts shown adapted to carry ipeclfloation of Letters Patent.

Patented Dec. 30, 1919.

Serial No. 879.505.

groove in the face of the gear blank to allow sufiicient clearance for the cutting ,tool.

The first gear wheels made with curved teeth were cast and were of very limited utility on'account of the relative inaccuracy and weakness of cast gear teeth. Later, it was proposed to machine such gears by sweeping a formed cuttin tool across the face of a gear blank and imparting to the gear blank a tilting movement along a line assing through the tooth space being cut.

his process, however, does not produce gears that will mesh with even approximate correctness because the tooth spaces so produced are unsymmetrical and the tiltin of the gear blank serves to correct such laci of symmetry at onlytnc' Point in the tooth curve, that isto say, at the point at which the axis of symmetry of the path of the cutting tool coincides with a diameter of the gear blank The tilting of the blank has the further disadvantage thatit causes a sharp break at about the middle line of the curve of each tooth face, anexcessive amount of metal being cut away above and below this line. For these reasons, gear wheels'cut by the process just described will not transmitunitorm angular velocity.

If a cutting tool is associated with a gear blank in such a manner that the tool and the blank have a'mutual rollin movement similar to that which takes 1 so between a cooperating rack and pinion, the cutting tool will generate accurate gear teeth in the blank. 7

-Accordingto my present invention, I'apply this principle to the cutting of nonrectilinear gear teeth by causing a cutting tool to sweep in a curved or other nonrectilinear path across the face of a gear blank and simultaneously imparting to the blank a generatin movement; that is to say, a movement whic determines the outline of the gear tooth bein out. When generate gears are mentioned herein, I desire to;be understood as referrin to gear-sin which the tooth form results: .rom a mutualmoves ment-between the gear blank and the cutting tootduring the cutting operation. In the epecific modification of 7 my invention which ,El shall describe tindetail, a rotary hollowv milling tool; is broug t into cutting e fie sm rt with t e f ce i of a s a bl n W. 6

. arotstehla rmrwasmascams perpenfiiculer to'the "axis aboutwhich the cutting tool rotates.

Inorder that the slots. between the teeth ay be i ermn d r h ee e to 9 .11 impart to the cutting tool and to the blank 2. bodily rolling movement with respect: to each other during the operation of cutting eqht t Eh iii t ch tea 119m abcimatbrizcnta axis arid the blah is supported upon a vertical smis i maiy cause the blank to simultaneously rotate and to xneve bodily pest the cutting tool while in cutting engagement therewith, this rolling movementof generationbeing'similar to the relative movement which takes place between a cooperating pinion'and stationary rack. The movement of the gear blank is analcgous to'th'at of'the piniomand the cut ting tool cooperates with the gear blank in the m'annel ofi a rack tooth.

After each tooth is generated in the mam nerjust described, the tlank *ls withdrawn from engagement with the tool and returned to its initial position, given an indexing rotation, and again brought into engageinent with the rotating tool. A four-Way bodily movement is thus imparted to the as each teeth is cut.

'An 'ually efl eetive modification of my process eonsists in bodily-movin the cutting tool instead of the blank, In t iscase, the

blarlk retates Without bodily movement and the rotary tool iegiven a four-way bodily movement, "durin "the cutting of each tooth, similar'to the four-Way movement imparted to the gear blank in the first form of the proeess above described. Inboth forms,

the speed of transhttion of the blank or of the tool duringl the cutting operation is made equalto e speed at which the gear blank rotates, measured upon the circumfer ence of its pitch'circleor upcln that of its base" ei' rcle,*"depending' upon whether the bllinkfis out with rcrcecuceto the pitch circle or to the haserirclei The result is that, if the blank or the tool moves bodily adistahtie equal to'the circumference of the (ircleofi'llo that ef"tlle base circle of the blank, as thecase may befthe blank will have completed t e revolution.

For a better understanding of my inventioh, rcreeenee may now behad to the ac companying drawing, which illustrates a machine adaptcu to carryout the form of In)? in Whichthe rotarfmilling tool ienet Bodily movable; While the'blan k both retatesfsndi erfcnes the rmrevtay bodily nievtmtee some (resented? miemsldlfinilllistrflfid'ii'i Figsl and 2 is ssentially a hi illlhghieglhiiit-Fof a ten knew type, having a ntegrate! cutting We a li afl wofikllold ing n teness crest-{enticed Y 1 carrying.- at eet use, a egency aejeeatle t ence weed pmeeeems aeacpperesaweh hearings 3 and 4 in which is mounted a spindle 5 that carries a cone pulley 6, with which a driving belt 7 is adapted to cooperate to rotate the spindle 5. The spindle 5'carries, at its outer end, a circular hollow milling tool 8, the radius of which corresponds to the radius of the teeth to be cut.

7 The milling tool 8 may conveniently becomposcd are number of removable cutting tools setin a circular holder, and together presenting the appearance shown in Fig. 1.

Mounted in transverse ways Grand 10 on thebracket 2, is an elongated bed 11, which is adapted to'be moved toward and from the standard 1 by means of a screw shaft 1.2 which cooperates with a screw-threaded projection depending from the bed 11 and is adapted to be turned by means of a hand whee] 1.4. The bracket 2 and the bed 11 may be adjusted vertically along guides 23 in the standard l by means of a screw 15 that cooperates with a stationary nut 17 held in a projection 18 of the standard 1. The screw 15 is adapted to be turned by means of cooperating miter gear Wheels 18 and 19, the gear Wheel 19 being secured to one end of-a horizontal spindle 20 that is provided with a squared end 21, to which a wrench may: be applied.

The-bed 11 is provided (with longitudinal slots 22 in which a head stock 24 is adapted to move. The head stock 24 isprovide'd with bearings for supporting a vertical spindle 26 that is adapted to support algear blank 27 in operative relation tothe cutting tool 8.

Means are provided for causing the head stock 24 to travel lengthwise upon the bed 11 and for simultaneously causing theblanksupporting spindle 26 to rotate. As shown, suchxnieans comprises a screw shaft 28, the ends'of which are supported in bearings 29 and 30 in the bed 11 and which on serew threadedo nings'S-I in the head stock 24;. The screw 8 aft 28 isprovid-ed, at the operating end of the'me chrinawith a crank 32. y it will be obvious that when the screw shaft-28 is turned by means oi the crank 32, the head stoek 24 will be caused to move longitudinally upon the bed 11.

To the screw shaft 28, near the crank 32, is secured a spur gear Wheel 33 to mesh with a spurgear-wheel al that is to one endof a spindle shaft 85 "which is disposed pemllcl to these'rew' shaft 28 and-somewhat above it and to the right; as seen in Fig. 1. Featherednponthe shaft 35 is a worm pinicneete mesh'with a'wm'm wheel 37 that is secured to the inner end of a short hollow shaft '38 which is rotatabljr mounted a bearing in the wall of the head stock 24 and carriesyat its outer end, an indexing plate 391" Kiel-rar fied extends through the short hollow she lites endencies, at its outer end, e'erank il flhac isprorided with a spring- 3 pin'AB- with-per-iera-= head stock is ther by moved inthe direction of the arrow 6, Figrfiw-uml reaches it t rtm position, shown lnfllilg. 3. Durin -f1h1-$ return movement of translation, the b 11 k is oausedm rotate in the 011- rection of the arrow f, Fig. 6, to the angular p sition which it otoup ed when th machine was startedi The blank is thtn iiidexed by means of the indexing crank 41, and the cycle of operations i agaiu begun for cutting the next tooth, the posltion; f which is indicated in dotted lines, at v76, F .6- r v When abut-hes been made for each moth spaceofi the ear blan-h'the cutting: tool 8 should be replaced by another cutting tool, the interior Faidius oi which is equal to the external radius oi the first cutting'ttool used, in order that both 'theconcave and convex faees 01' the a-r teethshnll have equal radii. This math .oi cutting with two cutting tools produces gears that are adaptedato mesh with one amother interchangeably. It is, however, pnssible to cut :1 pam of gears that will mesh accurately by cutting one of them with asingle cutting tool and cutting the teeth on- :the other with two patting tools of unequal radii corresponding respeotiveiy.,: to the inner'a-nd outer radii ea? the sin letool withwhichjthe first gear was cut. 'l his method is economical in cases where, for example, a; large air wheel is to mesh with a small pinion, t e large wheel being out with a single cutter, and, the pinion, which has fewer teeth, being shaped accordingly with; two cuttem In practice, it is frequently desirable tame a third cutting tool for ranging out the tocthspaces, Whlch are then ished by meansiof accurate fininshing cutters of the properradii.

According to my prooessyteeth havin a ious deg ees of urr tugie may een upon hlanlts- .of various. diametem; The minimum dlametels oi thezcutting tool that can be used with a givenqgear blank isg'ideormin d by t e 0f the b r ifi y im he cuttiaa-g toolmst c e n he h rd angen t thfi l'fifltrioiqcle t this tooth'fit the edge of he face f he blank, s E gv The breadth of the face oi the blank re imd y th di mc et i, theeu tig toet The foregoing description ates pan tieularly to'gear teeth cut with irefierenceto the; pitch line oi the gear. 7 if the cutting tool is of the form shown in "Figt'JL, the teeth pl'ddmiced gave of exact involnte form at the: tooth@,auia1s and ary ptogrea sifvely fromthisto aihyperbolf o format the ends cf the teeth This variutiofi fr m true intimate-shapeis emeedimg}y SM and 911 1563 no (iifiieflty in the-opemtiemot tin? gents espeo aliyg Mame -inc pair at meg Big-Q8818, therphgiit demtions trim tweet voluttgferms in the two mt hmgmemm minimise Wendi-i1) "a fleet of a pair at true invqlute are. It, however, ear teeth of true invo ute arm m a 1. wa er 9 mp a P n; 0 We tmatvq t t-an 8}? cf t e em; shpwi in at/ aadfita d mwut e th Wlt stanc o he hate lin d h g t; b a Inthis ase onlyfthe paints g ofthe cattm t ols ed m t e at mgcp at m I r whee tarauto be out, thee ttf tool unfit: blank are so assotiatedtlia a face of th cutting tool isit ngenttot 9 se eirel o the blan In h s modifi ation of my process, hetc tt ng peration must be owe beiore thacut ng book s r lledv omp l ely ugh the: time n: ord z th 00 math f th oc a e s d o the tooth 12 m y not be out ay- Itthebase circle f the gear blank coincides with its root circle, this P ocess pro e g a too h t are ot true involute term in all their parts. If the base circle and the noot-eireledo not coincide, the tooth spaceswill bladeeper in the terthan at the. ends, but, from thetops o i he teeth to their effective roots, they are'of true involuteformi i A 7 While I-havedeecribed a process iii-which the geamblamik is moved in ordea? toaefieet theeaamion of the teethtit is to, b undemtood that any robese m tostr ttod te this form, but includes as Well the modiifi cation in which the toelis both rotated and bodily moved, While the gear blank rotates during the cutting operatiom Thesetwo forms acoomplish'idonticalresults, since the relative movement between the tool and the blank is the same in both cases. It is also abviousthat he infilds which sup pbrt the tool and the blan may not be horizontal and vertical, respectively, but mayoceupy any desired POfitiOIISySOlOHg as their; relax tiv'e position and movement remainthe same. In view .01! the H utnerous modifications-of which my intent on'is culpable, I desire thatit'be unilyiby- Such tions as" are indioatedt in the appended I clainidsmyfimithtioha I a gear cutting; machine the comht nation with a cutter oifia bed; when} week movabie longitudinally'oi the beet, t'hlank spindle meuntcdoli Bait headstock-Jimmie operating to move thehbad'stock longitudinallyt of the bed for traversing a blank put said cutter, and meansfor rotating the blank during such traversing 1121013011 comprising a worm mountcdon thehead stock and operatively 'lcohnected (with: Ztaid la k spind tmtum flsle same eaifl Hotmnheing movable with thc-headrstotk, and airotary shaft lpq'm whickahe woe-mic teatberbdto mflnit :relative sliding? movement bltweenthe. w rmm'd :fimhafit mime zdriine said worms from the filth! manta hash i18 movable longitudinally of the bed, a blank spindle mounted on said head stock, means operatin to move the head stock longitudinally o the bed for traversing a, blank past said cutter, and means for rotating the blank during such traversing motion comprising a worm mounted on the head stock and geared to the blank spindle, a worm gear also mounted on the head stock and rotatable With said Worm, a second Worm in engagement with said Worm gear, and a ro- In testimony whereof I have hereunto 15 subscribed my name this 22nd day of Dee, 1914.

JOSEPH O. OBRIEN.

Witnesses:

R. T. MILLER, B. B. Hume. 

